6wks preg, concerned about dark brown discharge (1st preg)

Hi, I'm 6weeks pregnant and for the past 8 days I have had dark brown discharge. I have read that brown discharge in the 1st trimester is normal as it's old blood and could be for example a sign of implantation bleeding, however it's been 8 days now and it seems to be heavier as the days go. it started out pretty light (barely there) and now it's pretty heavy. not as heavy as a full on period though, but I'm quite surprised by the amount, especially today. I havnt seen bright red or 'fresh' blood but still wondering if I should be concerned? My first OB-GYN appointment is set for 8 weeks, should I see a doctor sooner?